Visual MODFLOW Flex

Groundwater Flow & Contaminant Transport Modeling Software

Visual MODFLOW Flex brings together industry-standard codes for groundwater flow and contaminant transport, essential analysis and calibration tools, and stunning 3D visualization capabilities in a single environment.

Visual Modflow for Groundwater Flow & Contaminant Transport Modeling Software

What's New in Visual MODFLOW Flex 8.0

Experience the new version release of Visual MODFLOW Flex 8.0
See what was included in Visual MODFLOW Flex 7.0
For a complete version history, see the Visual MODFLOW Flex readme file


You can now add more types of observations to your groundwater modeling projects:

  • Observation Types: the following observation types are now supported
    • Wells/Points: head, concentration
    • Boundary Condition Flow: net volumetric flow exchange between groundwater and a specified boundary condition
    • ZoneBudget Zone Flow: net volumetric flow exchange of groundwater in/out of a specified zone, between a specified zone and another zone or a specified boundary condition type
    • Stream (SFR): stage, depth, outflow, head difference between stream midpoint and associated groundwater cell centroid, flow diverted (diversion segments only ), groundwater head, streambed seepage through the unsaturated zone
    • Lakes (LAK): stage, volume, inflow, outflow

Observation for Groundwater Flow & Contaminant Transport Modeling Software

Calibration and Run Result Visualization

  • Visual MODFLOW Flex includes a new model results dashboard to facilitate model calibration and results interpretation:
    • Model Dashboard: model observations and associated model results can be displayed in the new model results dashboard which includes dynamic tabulation and charting of results:
      • Tabulated results: observations and corresponding simulated results are presented in a tabular format with dynamic filtering. Tabulated observations include observation metadata, including time, location, observation group/type, model layer, and conductivity zone so that you can quickly display all the data or limit the view to what is relevant.
      • Charts: simultaneously display one or more charts including:
        • simulated vs observed values to evaluate model calibration/history matching
        • time-series to display and evaluate transient result

      Visual MODFLOW Flex 8.0 - Calibration

      • Text Outputs: all observations and associated simulated results are output as tab-separated variable text files for use in both Visual MODFLOW Flex and in external applications.
      • Flooded Cells: Display cells with simulated heads above the top of the model as a flood depth map or as a solid color to facilitate model calibration and interpretation:

      Visual MODFLOW Flex 8.0 - FloodedCells

      • Easily switch the location of subviews in Flex Viewers so that you can customize the layout.

Packages and Model Runs

Visual MODFLOW Flex includes the following improvements for working with your models:

  • Single Engine Runs: run a secondary model such as transport, particle track, or zone budget simulation without having to rerun your flow model.
  • Update Solvers: update your flow model solvers without having to retranslate your whole model
  • Copy Property Zones: copy/paste zones from one material property zone type to another so that you can more easily have consistent material zones across property types such as conductivity, storage, and transport parameters
  • Default SMS Settings: the default settings for the SMS solver package in MODFLOW-USG have been updated based on recommendations by the author of MODFLOW-USG
  • Gage Package: gage package is supported in models using the surface water network workflows for streams (SFR) and lakes (LAK).

Surface Water Workflow

Visual MODFLOW Flex includes a new calibration dashboard:

  • Conceptual Workflow: Build surface water stream and lake networks in a conceptual model and convert it to numerical models
  • Clone Workflow: surface water workflows are copied into applicable runs when editing a grid or cloning a model run

Data Handling

Greater control over your project modeling data:

  • Data Operations: data objects use the expression builder, facilitating greater control and flexibility when adjusting data object elevations for surfaces, points, polylines, and polygons.
  • Expression Builder functions: added a function called ifgaps() to handle expressions with non-overlapping surfaces – now you can combine surfaces with different extents/scales such as regional and site surfaces using a single expression.
    Data Handling
  • Horizons: are now treated the same as other surfaces: they can be shown in 2D views with control over display settings
  • Cell Inspector Feedback: Typing a cell ID in the cell inspector provides (optional) feedback on where the specified cell is located in the active view
  • Export more data objects:
    • Grids: shapefile,
    • Output Comparisons: shapefile, contours, and surface
    • Horizons: surfaces
    • Water Table: surface

Performance, Usability, and Other Enhancements

Improved speed and performance for the following:

  • Loading and editing model properties and boundary conditions in larger models
  • Using the Cell inspector
  • Model Translation

Greater control over your project modeling data:

  • Backup your project and related files as a zip file from the Main Menu to archive your project or easily share it with colleagues.

Visual MODFLOW Flex 8.0 -Define particles -Backup your project




  • Generate all grid types from the Model Domain context menu of conceptual models
  • Define particles around screens of non-vertical wells in the 3D plane perpendicular to the well stem

Visual MODFLOW Flex 8.0 -Define particles

Defects Addressed

The following issues have been addressed:

  • Changing numeric values in color ramp settings has no effect
  • Improper validation when importing a model that uses the BCF package having inactive cells with 0 thickness causes model runs to fail.
  • Pilot Point values not correctly assigned using property values from the model leading to issues with preferred-value Tikhonov regularization
  • PEST implementation incorrectly assumed pilot points were present in all layers and was corrected to only assign pilot points to cells/layers in their respective zone.
  • ZoneBudget fails to run if Conceptual Model name has leading or trailing spaces
  • Flow model translation fails if the SFR workflow schedule/data is empty. Flex will now skip SFR translation in this case.
  • Project files grow after each save
  • SFR2 Feature layer order and symbology does not persist after closing and reopening the project
  • WEL package disables MNW2 translation in some cases
  • Error assigning MNW wells to numerical model in certain cases
  • Flex fails to create child grids in one-layer grids
  • PEST workflow does not create Variograms when some layers do not contain a zone.
  • Quality and aspect ratio of exported images from 2D views was incorrect
  • DRT package not included in run using Advanced translation settings
  • Layer View is corrupted in some cases when viewing T=1 in View Maps step
  • Surface Water Workflows are not included in cloned runs present in the original run
  • Insufficient validation at translation may lead to LGR models that fail because dry cells propagate to the interface between parent and child grids.
  • MODFLOW-SURFACT BCF package translation formatting is incorrect for layers with negative elevations
  • Transport run window only reports up to 9999 time steps. The max number of reported time steps for a transport run is now 100,000,000.
  • Cannot extract a subgrid if the project has been run previously, but not in the current session
  • Importing well objects having measured depths resulting in negative elevations fails
  • During transport engine translation, .BTN file does not always honor the ‘Simulation time length’ value entered in MT3DMS translation settings
  • When a single 2D sub view is active at the view maps step, the view toolbar buttons may be hidden
  • Grid color cannot be changed in Flex 2D subviews
  • Export null values in dry cells/inactive cells does not respect user selection
  • Error while trying to import UCN files with unknown units
  • Error opening constant concentration in standalone viewers
  • Error trying to access color settings in certain numerical workflows
  • SFR dataset2 is missing cells during translation of model with certain topological configurations

Visual MODFLOW Flex Applications include

  • Delineate well capture zones for domestic water supply development
  • Design and optimize pumping well locations for mine dewatering projects
  • Determine contaminant fate and exposure pathways for risk assessment
  • Simulate surface water-groundwater interactions
  • Watershed scale/regional groundwater modeling, and aquifer storage and recovery (ASR)
  • Evaluate groundwater remediation systems (pump and treat, funnel and gate etc)
  • Evaluate saltwater intrusion

Why Choose Visual MODFLOW Flex?

Build models faster and more efficiently

  • Model inputs and grid design can be updated at any point in the modeling process as modeling objectives change, more data are collected and a better understanding of the sub-surface is achieved.
  • Modeling steps are conveniently presented in an intuitive, workflow-driven graphical user interface: see current and completed steps, and steps you need to finish.
  • GIS-based 3D conceptual modeling and numerical modeling all within a single integrated software environment. This reduces costly 3rd party pre-processing tools, and eliminates transfer errors.

Build larger, more complex credible models

  • Equipped to handle vast quantities of detailed, high resolution data. Simulate large and complex regional-scale groundwater systems.
  • Model inputs and outputs can be easily visualized alongside raw GIS field data in 3D, allowing credibility by demonstrating numerical model data generation (model layers, flow parameters, recharge data) from conceptual data (borehole logs, GIS data).
  • Unique design permits easy side-by-side comparisons of multiple models allowing you to assess alternative modeling scenarios, grid indiscretions and hydro-geologic interpretations.

Powerful Data Visualization

Built and designed on the latest in 3D visualization technology, Visual MODFLOW Flex allows you to effectively present and communicate your data to colleagues and stakeholders with impressive visual renderings of your hydrogeologic model.

  • Visualize all data, including conceptual objects, numerical grids, input data (property zones, boundary condition cells) and output data (calculated heads, pathlines, water table) in state-of-the-art 2D, 3D and multi-view (FlexViewer) displays.
  • Create cut-away and cross-sectional views that allow you to see inside your model.
  • Generate 3D animations and movies for reports or the web, and optimized OpenGL graphics for enhanced hardware rendering.
  • Add isolines, contours, pathlines and color shading to viewers.
  • Drape raster images (site maps, satellite imagery) over 3D surfaces to show relief

Efficiently Manage Multiple Models

Most modeling projects involve several scenarios/versions, e.g., steady-state vs transient, different properties, inputs and grid types. Visual MODFLOW Flex allows you to assess uncertainty and improve model credibility through comparisons and analysis of multiple modeling scenarios – all within a single project.

  • Manage multiple model scenarios in a single project, and make direct visual and numerical comparisons between different modeling scenarios.
  • Easily generate multiple models in parallel for evaluating alternative hydrogeologic interpretations and hypotheses.
  • Calculate head differences between multiple model runs, with the same or different grid size.
  • Compare and analyze multiple modeling scenarios for selecting the best, most realistic model.

Full GIS Integration

Easily construct your grid-independent hydrogeologic conceptual model in minutes using existing GIS data sets.

  • Quick and easy data importing of all common file types and formats.
  • Automatic coordinate system and units conversion on import, and automatic data validation and intelligent error checking on import.
  • Define model boundaries, property zones, boundary conditions and attributes from imported GIS data.

woman in front of screen

Integrated 3D Conceptual and Numerical Groundwater Modeling

Visual MODFLOW Flex provides a seamless transition from raw data through conceptualization to the numerical model all within a single intuitive modeling environment.

  • Define complex geology and model layers using borehole log data and cross-sections
  • Interpret GIS data to define hydrogeologic properties and boundaries independent of the grid
  • Run, analyze, and validate model results with raw data in 2D, 3D, and cross-section views
  • Easily create multiple conceptualizations; generate numerous grids and model scenarios in parallel all in a single project
  • Assess uncertainty though comparing heads from multiple model runs in 2D, 3D or chart views

Flexible Grid Options

Visual MODFLOW Flex provides various grid types from which you can generate your numerical model. Easily experiment with different grid types and choose the one that gives you the best, most stable model.

  • Choose from various structured and unstructured grid types to accommodate a wide range of applications and geologic conditions (e.g., pinch outs, discontinuities).
  • Improve simulation accuracy, reduce runtimes and increase model stability with unstructured grid types (MODFLOW-USG)
  • Easily generate multiple grids within the same project and compare side-by-side in 2D or 3D
  • Perform grid refinement around areas of interest
  • Create faster more stable models with nested child grids that contain local horizontal and vertical refinement (MODFLOW-LGR)
  • View all supported grid types 

Get Started With Visual MODFLOW Flex